There exists a continued risk of exposure to infectious agents by health care workers who are continually utilizing hypodermic syringe assemblies for injecting patients with medicaments. Because of this situation, it has been recommended that all needles used by health care workers should be regarded as potentially infective and handled with extraordinary care to prevent accidental injuries. Health care workers are advised to place disposable needles in puncture resistant containers. However, it is practically impossible to place puncture resistant containers in every patient's room and every office of a medical facility.
The U.S. Pat. Nos. 3,134,380 to Armao, issued May 26, 1964; 3,658,061 to Hall, issued Apr. 25, 1972; and 4,139,009 to Alverez, issued Feb. 13, 1979, all relate to hypodermic needle assemblies which attempt to shield a used hypodermic needle after use. The Hall patent discloses a catheter needle guard unit including a hub with a needle affixed thereto and a needle guard including a sleeve member with a longitudinal slot adapted to snap over the entire length of the needle. In operation, the needle guard is in the open position when the needle is used to make a venipuncture in a patient and snapped into the closed position manually by a finger of the operator after withdrawal of the needle.
The Armao and Alverez patents both disclose retractable needle guards which extend over the length of the needle assembly prior to use and are retracted as the needle is inserted into the patient.
A device manufactured by ICU Medical, Inc. of Huntington Beach, Calif. and marked "ICU High Risk".RTM. includes locking members mounted on the needle shaft and a shield which has a neutral position wherein the shield is disposed against the hub and an extended position wherein the shield is disposed over the tip.
The Armao, Alverez, and ICU Medical, Inc. assemblies all include a shield which covers a significant portion of the needle shaft during use of the needle for an injection. Hence, the assemblies either have less usable needle length if a conventional needle is adapted to the assembly or the assemblies require a significantly longer needle shaft. Additionally, all of these assemblies leave the tip of the needle exposed or capable of being exposed. The tip of the needle is not locked in a completely enclosed guard.
The U.S. Pat. No. 4,735,618 to Hagen, issued Apr. 5, 1988, discloses a protective enclosure for a hypodermic syringe having a needle guard connected to a hub portion by two pair of pivotally moveable arms which operate to permit the needle to pass through a central channel during injection and rest in a needle pocket when injection has been completed. Similar to the aforementioned devices, the Hagen patent provides a needle guard having an extended neutral position. The needle guard must be forced back along the needle shaft during injection.
The U.S. patent application Ser. No. 082,483 to the applicant of the present application filed Aug. 7, 1987, now U.S. Pat. No. 4,790,828, discloses a disposable needle assembly including a cap having a neutral unstressed position proximate to the hub of the needle exposing a length of the needle portion and an extended stressed position wherein the cap is biased towards the neutral position for irreversibly capping the distal tip of the needle. A tether connects the cap to the hub portion.
The present invention provides an improvement to the self-capping needle assembly disclosed in applicant's prior patent application by providing an assembly adapted to be used in combination with a catheter. Further, the present invention provides improved forms of tethers for connecting the cap to the hub portion of the needle.